| Hydrocephalus describes a neurological condition where Cerebrospinal fluid (CSF) accumulates in the brain causing enlargement of the ventricles. Even after treatment with a surgically implanted shunt, monitoring techniques like Magnetic Resonance Imaging (MRI), Computed Axial Tomography (CAT) are expensive. Transcranial ultrasound is generally not used in patients beyond infancy, due to scattering and absorption by the skull. However, recent work indicates frequencies below 2 MHz can penetrate regions of thick skull and detect reflections from within the brain. This project assesses the use of an ultrasound-based diagnostic monitoring technique to detect enlargement of the lateral brain ventricles.;An underwater computer-controlled 3-dimensional positioning and data acquisition system was created. An impulse pulser-receiver with a planar 1 MHz transducer was used to acquire pulse-echo measurements through human skull and into a gel brain phantom developed for the study. Polygel (Whippany, NJ) was selected as the brain phantom material for its pliability and approximation to brain tissue. The phantom brain was cast from an anatomically-derived mold of the cerebral ventricle to determine if volume changes in the lateral brain ventricle can be detected through the skull. A syringe was used to fill the ventricle and induce 1 ml incremental volume changes that imitate hydrocephalus. Windowed cross-correlation techniques were used to calculate displacement between the brain phantom and ventricle interface as an accommodation to increasing fluid volumes. This work establishes the feasibility of using single-channel low-frequency ultrasound to detect changes in ventricle size. Such technologies could be useful in producing small devices for monitoring for hydrocephalus as well as other disorders in the brain. |
